Electron microscope radioautographic identification of serotonin-synthesizing cells in the mouse gastric mucosa.
This study correlates the fine structure of mouse gastric endocrine cells with their ability to synthesize serotonin (5-HT) from 5-hydroxytryptophan (5-HTP). Mice were sacrificed 2 hr after the intravenous injection of 5-HTP-(3)H or 5-HT-(3)H. Their stomachs were processed for light- and electron microscope radioautography in a manner which retained labeled 5-HT while washing out other labeled substances. Stomachs from additional mice were incubated in vitro with 5-HT-(3)H and processed similarly. All morphologic types of mouse gastric endocrine cells exhibited a similar facility to incorporate exogenous 5-HTP and to convert it to 5-HT which was bound intracellularly. Differences in densities of silver grains observed over endocrine cells suggested that individual endocrine cells indeed varied in their ability to synthesize and/or to bind 5-HT; such variations, however, were not reflected by differences in fine structure, with the exception that endocrine cells with few granules always contained little newly synthesized 5-HT. The newly synthesized 5-HT was associated with the intracellular granules. The gastric endocrine cells were not labeled by exogenous 5-HT-(3)H, whereas mast cells were labeled by either 5-HT-(3)H or 5-HTP-(3)H administration. The findings of the present study support the position that the gastric endocrine cells represent a single cell type, at least in respect to serotonin metabolism-that the argyrophil or argentaffin reactivity of these cells merely reflects their amine content at a given time.
D006916:5-Hydroxytryptophan / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D004721:Endoplasmic Reticulum; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism*; D006056:Golgi Apparatus; D006651:Histocytochemistry; D007275:Injections, Intravenous; D008407:Mast Cells / Q000378:metabolism; D008722:Methods; D051379:Mice; D008854:Microscopy, Electron; D011708:Pylorus / Q000166:cytology; D012701:Serotonin / Q000032:analysis / Q000096:biosynthesis*; D014316:Tritium
D014316:Tritium; D012701:Serotonin; D006916:5-Hydroxytryptophan